This invention relates to an automatic vending machine and, more particularly, to a control system used in the automatic vending machine.
Generally, an automatic vending machine includes a display device for displaying sales information such as the amount of deposited money, a commodity discharge device for controlling the discharge of commodities, and a coin validator for identifying the validity and the denomination of a deposited coin. The display device, the commodity discharge device, and the coin validator will be called herein controlled devices, respectively.
A control system of the type comprises a plurality of terminal control units coupled to the controlled devices, respectively, and a main control unit connected to each terminal control unit through a communication line known in the art. In the above-mentioned control system, the main control unit supervises and controls the terminal control units. Each of the terminal control units controls a corresponding one of the controlled devices in accordance with the content of communication with the main control unit. Each terminal control unit comprises an arithmetic unit, a memory unit, and an input/output unit for the controlled devices and the main control unit, and is operable in accordance with a control program memorized in the memory unit.
In the control system, it is assumed that modification is required in specification of each terminal control unit. In this event, the control program is changed into a new control program in response to the modification by replacing the memory unit with a new memory unit. Specifically, an ROM as the memory unit is removed and a new ROM with the new control program stored therein is mounted.
In the control system, if the control program memorized in the memory unit must be changed into a new control program in response to modification in specification of each terminal control unit, the memory unit itself is replaced by a new memory unit. Specifically, an ROM as the memory unit is removed and a new ROM with the new control program stored therein is mounted.
However, such replacement requires much time and labor and, in some cases, will cause any trouble such as bending and damaging of a pin of the ROM. In particular, each of the terminal control units is arranged adjacent to the controlled device corresponding thereto. The controlled devices are distributed at various positions in the automatic vending machine in dependence upon their functions. Therefore, if the terminal control unit is arranged at a difficult position uneasy to reach, the replacement of the memory unit often requires very much time and labor. In case where the memory units are replaced collectively for a plurality of terminal control units, the exchange operation must be carried out one by one and one after another. This requires extraordinarily much time and labor. In addition, there is a risk of incorrect replacement of the memory units.
Taking the above into consideration, proposal is made of a control system using an EEPROM (Electrically Erasable Programmable Read-Only Memory), which is electrically rewritable, as the memory unit of the terminal control unit. In the proposed control system, each terminal control unit comprises a connection unit capable of removably connecting a memory card. In addition, each terminal control unit has a rewriting program. The memory card with a new control program preliminarily stored therein is loaded in the connection unit. Then, the above-mentioned rewriting program is executed to renew the control program memorized in the memory unit into the new program stored in the memory card. In the above-mentioned method, it is possible to relatively easily update the control program without the complicated operation such as the replacement of the ROM. However, the latter problem described above can not be solved yet.